[Mimedefang] MIMEDefang 2.53-BETA-2 is available

David F. Skoll dfs at roaringpenguin.com
Tue Aug 30 20:19:34 EDT 2005

Kenneth Porter wrote:

> Any idea why the zlib authors don't want to support it? Is it patented
> or not-invented-here? (This is the first I've heard of deflate64.)

I didn't investigate zlib (Dave O'Neill did), and it seems that
they had to reverse-engineer deflate64.  Apparently, there were
comments in the code that it was experimental, unsupported, and
unlikely to be supported.

>From the zlib FAQ: http://www.zlib.net/zlib_faq.html#faq39

     39. Does zlib support the new "Deflate64" format introduced by PKWare?

     No. PKWare has apparently decided to keep that format proprietary,
     since they have not documented it as they have previous compression
     formats. In any case, the compression improvements are so modest
     compared to other more modern approaches, that it's not worth the
     effort to implement.

Unfortunately, the latest version of Winzip appears to offer the
"brand-new spanking cool honkin' nifty super-duper" compression option
(which is deflate64).  It pops up a warning that such ZIP files might
not be widely compatible, but gives you the option of suppressing the
warning in the future.

Our customers are seeing steady trickles of these undigestible ZIP
files. :-(



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